A multiple-input multiple-output (MIMO) technology is widely used in a Long Term Evolution (LTE) system. In a MIMO system, a precoding technology is usually used to improve signal transmission quality/increase a signal transmission rate. In an LTE system in a frequency division multiplexing (FDD) mode, a terminal determines downlink channel information based on a received channel state information-reference signal (CSI-RS) sent by a base station, and feeds back the downlink channel information to the base station. The downlink channel information includes a precoding matrix index (PMI), a rank index (RI), and a CQI. Currently, the terminal determines the downlink channel information based on an assumption of single user MIMO (SU-MIMO). After receiving downlink channel information sent by a plurality of terminals, if the base station determines to select the plurality of terminals to form multi-user MIMO (MU-MIMO), to reduce interference between the plurality of terminals, based on the downlink channel information fed back by each terminal and by using a preset algorithm (for example, a zero-forcing algorithm), the base station reconstructs a precoding matrix for the terminal, redetermines a rank of a channel, and allocates a corresponding CSI-RS port to the terminal. Because a CQI fed back by the terminal is based on the assumption of SU-MIMO, the CQI does not match actual downlink channel quality in a MU-MIMO scenario.
To resolve this problem, the base station precodes the CSI-RS based on the precoding matrix reconstructed for the terminal, and sends a precoded CSI-RS to the terminal. The terminal remeasures a CQI based on the CSI-RS, and feeds back the CQI to the base station. In this case, when remeasuring the CQI based on the CSI-RS, the base station needs to measure channel quality of a channel corresponding to each CSI-RS port (in other words, the terminal needs to measure, based on received information on a time-frequency resource corresponding to each CSI-RS port, channel quality of a channel corresponding to the CSI-RS port), and feed back channel quality of channels corresponding to all CSI-RS ports to the base station. However, actually, the base station needs only channel quality of a channel corresponding to a CSI-RS port corresponding to the terminal. Consequently, an uplink resource is wasted.